Dual rotary pump for power transmissions



INVENTOR. DUNCAN B. GARDI N ER BY ATTORNEY @4- smu snm l D. B. GARDINERDUAL ROTARY PUMP FOR POWER musursszons FIG. 2

June 23, 1953 Filed Dec 14, 1948 June 1953 D. a. GARDINER 3 5 mm. ROTARYPUMP FOR Pom mmxssron's Filed Dec. 14, 1948 DUNCAN B. GARDINER ATTORNEY4 Sheets-Sheet 2 Q I INVENTOR.

o. a sARomsn pwu. ROTARY PUIIP FOR PQIER TRANS||IS8ION.. I

Jume 23, 1953 t Quota-Shut 32 Filed Dec. 14, 199

DUNCAN B. GARDI N ER ATTORN EY June 23, 1953 v g; GARDNER 2,642,8 2

mm. ROTARY PUIIP FOR Pom Filed 1m. 14, 1948. simzwsum 4 FIG. 8

yaw, 1 11 I INVENTOR. DUNCAN B. GARDI NER ATTORN EY Patented June 23,1953 orrics DUAL ROTARY PUMP FOR POWER TRANSMISSIONS Duncan B. Gardiner,Detroit, Mich., assignor to Vickers Incorporated, Detroit, Mich., a.corporation of Michigan Application December 14, 1948, Serial No. 65,157

(Cl. l 34) 11 Claims.

This invention relates to power transmissions and is particularlyapplicable to those of the type comprising two or more fluidpressureenergy translating devices, one of which may function as a pumpand another as a fluid motor.

The invention is generally concerned with multiple pumping units and ismore particularly concerned with a dual pumping unit of the rotary vanetype. Unitsof this type are adaptable for use in hydraulic powertransmissions'having a plurality of fluid motors which must beseparately driven. Although each pumping unit is separately connected toa fluid motor for separately operating the same, the pumps may be drivenfrom a common prime mover and supplied with fluid from a single fluidsupply source. Multiple pumping units of this type are also utilizedwith control valves adapted to cooperate therewith in circuits wherein alarge volume of fluid is required against a fairly low pressure and atother times a smaller volume of fluid is required against a highpressure. The latter type of circuit is common in machine tool driveswhere a large volume of fluid is required for rapidly advancing amachine part to its working position and where a small volume of fluidis required for slowly feeding the part on its working stroke. "Inaddition, there are many difier- I ent hydraulic circuits which mayutilize a plurality of pumps in various other ways.

Multiple pumping units have been provided for circuits of the typementioned which have been proven eflicient and which are moreeconomicalthan the use of separate pumps because of combining in one compactunitary structure the multiple pumping units required for the purposesof the circuit. However, because of the great variety of circuits inwhich multiple pumpunits may be incorporated and the diflerent volumeand pressure requirements of each circuit it has been necessary toprovide a variety of multiple pumping unitsto meet the various circuitvolume and pressure requirements. One popular type of multiple pumpingunit of the dual rotary vane type comprises two pumping units identicalas to construction, each of which comprises a cam ring having an innerelliptical I 2 retained in their respective pumping recesses by separatemeans, usually by. head plates which have to be independently mountedand adapted to fit snugly in their recesses to insure equal distributionof clamping pressure over their respective units. 'In some cases, inaddition to separate ihead plates, bearing plates'are provided which aremounted independently of the head plate so as to avoid adjustment whichwould interfere with the clamping pressure and cause binding. a

The present invention obviatesthe use of separate bushings for eachpumpingunit by providing a valve plate common to both pumping units andalso avoids the use of separate head plates by utilizing a novelpressure head and ing engagement with the valve plate. The presentinvention avoids the disadvantages of other constructions whereitiisnecessary to mechanically adjust the clamping pressure to providefluid sealing engagement of the rotary pumping units. In this lattertype of. construction, well meaning, but negligent workmen frequently.pull up exposed bolts for adjusting head plates too tightly resultingin binding and failure of the pumping units. I

It is, therefore an object of this invention to provide an improvedmultiple pumping unit of the rotary vane type.

It is also an object of this invention to provide a dual rotary vanepumping unit which'is readily adaptable for interchangeability to meet avariety of circuit pressure and volume requirements. I

s It is also an object of this invention topro vide a dual rotary vanepumping unit which eliminates the use of separate supporting bushingsfor each pumping unit.

s It is a further object of this invention to providea dual rotary vanepumping unit'which also eliminates the use of any mechanical adjustableclamping means for maintaining the rotary pumping units in fluid,sealing engagement against their respective cooperating stationarybearing surfaces.

.It is an additional object of this'invention' to eliminate separatebushing elements for each'rotary vane pumping unit by providing a valveplate common to both rotors and to provide a fluid sealing engagement ofthe rotors with the valve plate by pressure responsive means.

It is also an object of this invention to provide a dual rotary vanepumping unit which is of an improved, simplified, compact, and reliableconstruction, which may be produced at low cost and which because ofinterchangeable features will meet a variety of circuit requirements.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Figure l is a longitudinal sectional view of a preferred form of thepresent invention on line ll of Figure 2.

Figure 2 is a top view of the present invention.

Figure 3 is a sectional view on line 3-3 of Figure l.

Figure 4 is a sectional view on line 4-4 of Figure 1.

Figure 5 is a sectional view on line 5--5 of Figure 1.

Figure 6 is a sectional view on line 6--6 of Figure 1.

Figure I is a partial sectional view on line l1 of Figure 5.

Figure 8 is a sectional view on line 8-8 of Figure 1.

Figure 9 is a partial sectional view on line 9-9 of Figure 3.

Figure 10 is a partial sectional view on line l0l 8 of Figure 3.

Referring to Figure 1, there is shown a dual rotary pumping unit l0having a casing which preferably is in three sections consisting of aright end section l2, a left end section l4, and a center section I6,all of which are connected together by suitable screws 18, two of whichare shown in Figure 2. The right end section I2 is provided with acommon inlet supply flange and the left end section with independentoutlet delivery flanges 22 and 24 for two pumping units of identicalconstruction but of different sizes, one of which is mounted in thecenter section l6 and indicated by the numeral 26, and the other ofwhich is mounted in the left end section [4 and indicated by the numeral28.

The pumping units 26 and 28, shown more clearly in Figures 4 and 8,respectively, comprise rotors 30 and 32, each of which carry a pluralityof reciprocating vanes 34 held in bearing contact with the innercontours of their respective cam rings l6 and 38, the former of whichcomprises the center section of the unitary casing. The rotors 30 and 32are mounted on a common drive shaft which is splined at 42 and 44 toprovide a driving connection for each of the pumping units. The casingsection [2 carries bearings 46 and 48 in which the shaft 40 is rotatablymounted and a suitable sealing ring indicated by the numeral 50.

The inner contours of the cam rings [6 and 38, which are respectivelyindicated by the numerals 52 and 54, are generally elliptical in shapeto provide balanced working chambers 56 and 58 for the larger pumpingunit and balanced working chambers 60 and 62 for the smaller unit.

The right end casing section is provided with an inlet passage indicatedby the numeral 64 which registers with the inlet connection 20(Figure 1) and which is branched, said branches being indicated by thenumerals 65 and 61 and each being respectively provided with an arcuateshaped port at its termination indicated by the numerals 66 and 68 andshown in Figure 3,

The ports 66 and 68 register, respectively, with 4 a portion of theworking chambers 56 and 58 of the larger pumping unit, and alsoregister, respectively, with a plurality of port holes 10 and aduplicate plurality of port holes 12 in the cam ring IS, the latter ofwhich are respectively located immediately adjacent to the workingchambers 56 and 58. The series of port holes 10 and '12 which extendcompletely through the ring l6 cooperate, respectively, with a pair ofarcuate shaped inlet ports 18 and in a fluid distributing valve plate orcheek plate 82 (Figures 1 and 5) which is mounted in the left end casingsection 14 so as to provide a supply of fluid to the inlet side of thesmaller pumping unit.

As shown in Figures 1 and 3, the plurality of port holes 10 and I2register respectively on the right side of the cam ring I6 with inletports 66 and 68 of the casing section l2 and on the opposite sideregister, respectively, with the arcuate inlet ports 18 and 88 of thevalve plate 82.

Referring to Figures 1 and 5, a curved passage 84 of the valve plate 82connects the arcuate inlet port 18 with an arcuate inlet port 86 on theopposite side of the valve plate 82 while a duplicate curved passage 88connects the arcuate inlet port 80 with an arcuate inlet port 90 on theopposite face of the valve plate 82. The arcuate inlet ports 86 and 90register, respectively, with a portion of the working chambers 68 and 62of the smaller pumping unit shown in Figure 8. In addition to thearcuate inlet ports located on opposite sides of the valve plate 82, thelatter is also provided with arcuate delivery ports 92 and 94 for thelarge pumping unit 26 (Figure 5) which extend completely through thevalve plate. The arcuate delivery ports 92 and 94 register on the rightside of the valve plate with the remainin portions of the workingchambers 58 and 56 of the larger pumping unit as shown in Figure 4.

Although the ports 92 and 94 should not appear in Figure 4, which is aview on line 4-4 of Figure l, the ports have been shown in dotted linesin Figure 4 for the purpose of illustrating the registry of said portswith the remaining portion of the working chambers 58 and 56. The

delivery ports 92 and 94 register on the opposite side of the valveplate 82 with an outlet chamber 96 which is formed in the left endcasing section l4 (Figure '7). As the ports are duplicates and registerwith the outlet chamber 96 in the same manner, it has been deemedsuilicient to show only one of said ports in Figure '7. The outletchamber 96 is connected directly to an outlet passage 98, the latter ofwhich registers with the outlet opening in the outlet flange connection2 The outlet chamber 96 is formed in the left end casing section I4 inthe following manner. The valve plate 82 is mounted in the casingsection [4 which is hollow. Mounted on the valve plate 82 is the camring 38 and a closure member I00. The cam ring 33 and closure member I00are fastened to the valve plate 82 by means of screws indicated by thenumeral I02. Thus, the outlet chamber 96 constitutes the space of theend section i4 between the outer peripheries of the closure member I08,the cam ring 38, and the exposed portion of the valve plate 82, and thewalls of the hollow portion of the section 14.

The valve plate 82 and also the cam plate 38 and the head plate Hillwhich are connected thereto, are prevented from rotary movement by meansof pins I04, one of which is shown in Figure 9 which extends through thelarge cam ring I6 and projects on either side thereof into The outerends of the vanes of the larger pumping unit 28 are maintained againstthe inner periphery 52 of the cam ring I6 by means of pressure. This isaccomplished by connecting the delivery ports 92 and 94 of the largerpumping unit 26 which are located in the valve plate 82 to a groove I06of the rotor 30 by means of passages I08 and I 09 and delivery passagesH8 and III in the valve plate 82 (Figures 4, and 7). As shown in Figure4, the inner ends of slots H2 within which the vanes 34 reciprocate arerounded, as indicated by'the numeral H8, and are connected to the grooveI06. Thus, pressure fluid delivered by the pumping unit 26 to thedelivery port 92 is delivered by the passages B08 and I09 to the grooveI05 while pressure fluid delivered through the delivery port 94 isdirected to the groove I06 by means of passages IE0 and HI.

Fluid delivery from the smaller pumping unit 28 is delivered to aseparate outlet passage H4 the" smaller rotor are identical inconstruction with that of the larger rotor except as tosize and'areroundedzat their inner ends as indicated at I32. The groove I30'is incommunication with the rounded portion of th slots and thus pressurefluid from the outlet chamber I 20 enters v the groove I30 through theplurality of holes which registers with the opening in the outlet flange22 as follows. Referring to Figures 1 and 6, mounted within the closuremember I00 is a pressure loaded cheek plate I I5 for a smaller pumpingunit 28 which contains arcuate delivery ports HS and l I8extendingcompletely through the plate. These ports are connected to theoutlet side of the pumping unit 28 on one side of the plate and on theopposite side of the plate are connected to a separate outlet chamberI20 of the smaller pumping unit which is formed within the closuremember I00.

The outlet ports H6 and H8 of the pressure loaded cheek plate H5 areshown in Figure 6 while Figure 8 discloses the manner in which the portsH0 and H8 register, respectively, with a portion of the working chambers82 and 60 of the smaller pumping unit 28. A telescoping fluid connectionmember I22, one end of which is mounted in a bore I24 ofthe casingsection I4 and the other end of which is mounted in a bore 526 of theclosure member I00 connects the outlet chamber I20 directly to theoutlet passage I I4. In addition the member I22 acts as a blocking valvein preventing fluid delivery from the outlet side of the large pumpingunit in outlet chamber 88 from entering the outlet passage I I4 of thesmaller pumping unit. It can be clearly seen that bore I24 is actually aportion of the outlet passage H4 and is connected to the hollow portionof easing section I4. By locating the tele: scoping fluid connectionmember I22, as illusrated, fluid delivered from the smaller pumping unitthrough the delivery ports H6 and H8 of the cheek plate H5 into theoutlet chamber I20 is directed through the member I22 to the outletpassage H4, and is prevented from entering the outlet chamber 95 oi thelarge pumping unit. Conversely, fluid delivered from the larger pumpingunit through the valve plate delivery ports 82 and 80 into the outletchamber 96 of the larger pumping unit is prevented from flowing into theoutlet passage H4 of the smaller pumping unit.

Means for maintaining the outer edges of the vanes of the smallerpumping unit 28 against the inner contour 54 of the smaller cam ring 38is provided by a plurality of holes I28 in the cheek plate H5 (Figure 6)which extend therethrough and permit pressure fluid from the outletchamber I20 to enter a groove I30 of the small rotor (Figure 8). Theslots for the vanes of I28 and maintains the outer edges of the vane inengagement with the inner contour 54 of the cam ring 38. 1

One of the most important features of the dual pumping unit is theprovision for automatically maintaining both rotors in fluid sealingengagethem with the single valve plate bypressure fluid means. As shownin Figure 1, it should be noted that the valve plate 82 is slightlyshiftable axially in' a mounting recess of the casing section I4indicated by the numeral I34." However, the valve plate 82 is maintainedby pressure fluid in the rightward position shown in engagement againsta portion of the surface area of the cam ring I6 and in fluid sealingengagement with the total surface area of one side of the large rotor30. Pressure fluid in the outlet chamber 06 of the large pumping unitacts against the leftsurface area of the closure member I00 and aportion of the outer surface of the valve plate 02 to maintain the valveplate 82 in fluid sealing engagement with the rotor 30. The totaleffective surface area included amounts to the total surface area of thevalve plate 82 minus the area of the member I22. If, for any reason, thepressure'in the outlet chamber is extremely low, the valve plate 82 isstill maintained in fluid sealing engagement with the rotor 30 by nieansof light springs I mounted in the outlet chamber 9801 guide pins I36 thelatter of which are mounted in the valve plate 82 and extend therefrominto the outlet chamber 98. g a

Separate means for maintaining the smaller rotor 32 in fluid sealingengagement with the opp site surfaceof the'valve plate 82 is provided'bythe cheek plate I I5, the surface area of one side of which is exposedto pressure in the outlet chamber I20 of the smaller pumping unit.

In case of extremely low'pressure in the outlet chamber I20, a lightspring I38 mounted in the outlet chamber I20 will hold the cheek plateH5 in fluid sealing engagement with the small rotor 32 and against aportion of the upper surface of the small cam ring 38. The pressureloaded cheek plate also maintains the rotor 32 in fluid sealingengagement with the valve plate 82. t

The check plate H5 is prevented from rotary movement by pins I40 shownin Figure 10 which are mounted in the cam ring 38 and extend therefrominto the closure member I00 and the valve plate 82.' Suitable sealsl42,I44, and I are provided, respectively, for the inlet flange 20 and theoutlet flanges I44 and I48. Suitable sealing rings I48 and I50 are alsoprovided for sealing engagement between the center section It and theend section casings I4 and I2.

In operation, with a suitable supply source of fluid connectedto theinlet flange 20, fluid will enter the inlet flange 20 and the inletpassage 54, the latter of which is branched and terminates in arcuateinlet'ports indicated by the numerals 66 and 68. As the rotor 30 isrotated by the shaft 40, fluid will enter that portion of the workingchambers and 58 in registry withxthe arcuate inlet ports and 68 of theend casing I2. Pressure fluid will be drawn into aeaaaoa a portion ofthe working chamber 6'0 of; the smaller pumping unit by means of theplurality of holes 10 in the center section l6, valve; plate inlet port18, passage 84, and port 86. Pressure fluid will also be drawn into. aportion of the working chamber 62 of the smaller pumping unit by meansof the plurality of port holes 12, valve plate inlet port 80, passage;88, and port 90. Pressure fluid will be discharged from the remainingportion of the working chambers 56 and 58 of the larger pumping unitthrough the delivery ports 94 and 92 which register with a portion ofthe working chambers, 56 and, 58 of the larger pumping unit. Fluiddelivery'from the delivery ports 92 and 94 of the valve plate 82 entersthe outlet chamber 96 of the larger pumping units and from the outlet.-chamber 96 is delivered to the outlet passage; 98 and through the outletconnection flange 24. Fluid delivery, from the smaller pumping unitisdelivered from the remaining portions of working chambers 60. and 62through the: pressure delivery ports H8 and I [6 of the cheek plate H5from whence fluid is delivered to the outlet connection 22 via thesmaller outlet chamber I20, member I22, and outlet passage H4. Themember I22 prevents fluid delivery from the larger pumping unit enteringthe outlet passage N4 of the smaller pumping unit and converselyprevents fluid delivery from the smaller pumping unit entering outletchamber 96 and, outlet passage 96 of the larger pumping unit.

As can be clearly seen, the pumping action of both pumping units issimilar to the vane pump described in the patent to Harry F. Vickers,No. 1,989,900. The shape and dimensions, of the working chambers of thepumping units cooperate with the shape. and arrangement of the inlet andoutlet ports to provide, vane pumps of the balanced type.

It is important to note that the use of supporting bushings have beencompletely eliminated. The construction of'the valve plate is such thatit cooperates with inlet passages in the right end casing section l2 andthe center section Hi to distributev fluid to the inlet side of thesmaller pumping unit. In addition, the valve plate contains deliveryports which connect the outlet side of the large pump to the outletchamber and outlet passages for the large pump in the left end casingsections. The'valve plate also cooperates in directing pressure fluid tothe inner ends of thevanes of thelarge pumping unit to maintain theouter ends of the vanes thereof in engagement with the inner contour ofits cam ring.

It is also important to note that the separate rotors are maintained infiuidsealing engagement with the valve plate by pressure fluid means. Inthe case of the large pumping unit pressure fluid from the dischargeside of the large pumping unit maintains the valve plate in fluidsealing engagement with the rotor of the large pumping unit. In the caseof the smaller pumping unit pressure fluid from' the discharge side ofsaid unit maintains the cheek plate in fluid sealing engagement with therotor and this in turn maintains the rotor in fluid sealing engagementwith the valve'plate. No mechanical adjustment, which in many cases results in pump failure because of excessive clamping pressure, isnecessary for maintainingthis fluid sealing engagement.

It should also benotedfthat several different combinations. of; sizes..of the different pumping units may be arranged. By mass productionmeans, a variety of sizes of each section may be provided which may becombined to meet the demands of a variety of volumes and pressures ofdifierent circuits. In this manner, separate dual pumping units to meeteach circuit requirement is obviated.

While the form of embodiment of the invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A dual vane pump comprising a casing having an inlet section and anoutlet section between which is a first pumping unit, means forming afirst pressure, chamber in the outlet section having an outlet passageconnected thereto. a first pressure responsive cheek plate in the firstpressure chamber, one side of which is maintained in fluid sealingengagement against the first pumping unit, a second pumping unit on theopposite side of the first cheek plate, each pumping unit includingmeans forming a pumping recess, a rotor in the recess, and a pluralityof reciprocating vanes carried by the rotor, said vanes being held inbearing contact with the contour of the pumping recess to form suctionand pressure working chambers, a common drive shaft for the rotors, aclosure member mounted in the first pressure chamber and forming asecond pressure chamber within the first pressure chamber, a secondcheek plate in the second pressure chamber and pressure loaded againstthe second pumping unit, means forming an inlet supply flow pathconnected to the suction working chambers of both pumping units, meansseparately, respectively, connecting the pressure working chambers ofthe first and second pumping units to the first and second pressurechambers, a second outlet passage in the outlet section, and meanshydraulically connecting the second pressure chamber to the sec ondoutlet passage.

2. A dual rotary pump comprising in combination a casing having twopumping units therein, each of which includes a stator and a rotorforming suction and pressure working chambers, a common drive shaft fordriving the rotors, means forming an inlet supply path connected to thesuction chambers respectively of both pumping units, means forming twopressure outlet chambers in the casing, one outlet chamber being insidethe other outlet chamber, means separately, respectively, hydraulicallyconnecting the pressure working chambers of the pumping units to thepressure outlet chambers, an outlet passage connected to the outerpressure outlet chamber, a second outlet passage for the inner pressureoutlet chamber, and means hydraulically connecting the inner pressureoutlet chamber to the second outlet passage.

3. A dual rotary pumping unit comprising in combination a casing havingtwo pumping units therein, each of which includes a stator and a rotorforming suction and pressure working chambers, a common drive shaft fordriving the rotors, means forming an inlet supply path connected to thesuction chambers respectively of both pumping units, means forming twopressure outlet chambers in the casing, one outlet chamber being insidethe other outlet chamber, means separately, respectively, hydraulicallyconnecting the pressure working chambers of the pumping units to thepressure outlet chambers, an

outlet passage connected to the outer pressure outlet chambena secondoutlet passage for the inner pressure outlet chamber, and a telescopingfluid connection member hydraulically connecting the inner pressureoutlet chamber to the second outlet passage.

4:. A dual rotary pumping unit comprising in combination a casing havingtwo pumping units therein, each of which includes a stator and a rotorforming suction and pressure working chambers, a common drive shaft forthe rotors, means forming two pressure outlet chambers in the casing,one outlet chamber being inside the other outlet chamber, separate cheekplates for each pumping unit in each'pressure outlet cham her andpressure loaded against their associated pumping units. means forming aninlet supply flow path to the suction working chambers of the 1 pumpingunits, means separately, respectively, hydraulically connecting thepressure working chambers of the pumping units to the pressure outletchambers, an outlet passage connected to the outer pressure outletchamber, a second out let passage for the inner pressure outlet oham--her, and means hydraulically connecting the inner pressure outletchamber to the second outlet passage.

5. A dual rotary pump comprising a first pumping unit and a secondpumping unit, each pumping unit including a stator and a rotor formingsuction and pressure working chambers, a common drive shaft fortherotors, a cheek plate between the pumping units in fluid sealingengagement therewith, means forming an inlet fluid supply flow pathleading to the suction chamber of the first pumping unit and to thecheek plate, means forming two separate fluid delivery flow paths, oneof which leads from the pressure chamber of the second pumping unit andthe other of which leads from the cheek plate, and a fluid supply portand a fluid delivery port in the cheek plate respectively connecting thesuction chamber of the second pumpingunit to the inlet flow path and thepressure chamber of the first pumping unit to the other fluid deliveryflow path.

6. A dual rotary pump comprising a first pumping unit and a secondpumping unit, each pumping unit including a stator and a rotor formingsuction and pressure working chambers, a common drive shaft for therotors, a cheek plate floatably mounted between the pumping units, meansforming an inlet fluid supply flow path leading to the suction chamberof the first pumping unit and to the cheek plate, means forming twoseparate fluid delivery flow paths, one of which leads from the pressurechamber of the second pumping unit and the other of which leads from thecheek plate, a fluid supply port and a fluid delivery port in the cheekplate respectively connecting the suction chamber of the second pumpingunit to the inlet flow path and the pressure chamber of the firstpumping unit to the other fluid delivery flow path, and pressureresponsive means connected to the fluid delivery flow paths maintainingthe cheek plate in fluid sealing engagement with both pumping units.

7. A dual rotary pump comprising a first pumping unit and a secondpumping unit, each pumping unit including a stator and a rotor formingsuction and pressure working chambers,

a common drive shaft for the rotors, a cheek plate floatably mountedbetween the pumping units, means forming an inlet fluid supply flow oneof which leads from the pressure chamber of the second pumping unit andthe other of which leads from the cheek plate, a fluid supply port and afluid delivery port in the cheek plate respectively connecting thesuction chamber of the second pumping unit to the inlet flow path andthe pressure chamber of the first pumping unit to the otherfluiddelivery flowpath, and separate pressure responsive means separatelyconnected to the'fluid delivery flow paths of the pumping unitsseparately maintaining the rotors in fluid sealing engagement with thecheek plate.

8. A dual rotary" pump comprising a first pumping unit and a'secondpumping unit, each pumping unit including a stator and a rotorforming'suction and pressure working chambers, a common drive shaft forthe rotors, a cheek plate floatably mounted between the pumping units,means forming 'an inlet fluid supply flow path leading to the suctionchamber of the first pumping unit and to the cheek plate, means formingtwo separate fluid delivery flow paths,

one of which leads from the pressurechambe'r of the second pumpingunitandthe othe'r'of which leads from the cheek plate, a fluid supplyport and'a fluid delivery port in the cheek" plate respectivelyconnecting the suction chamber of cheek plate in communication withoneof the delivery flow paths for maintaining the cheek plate in fluidsealing engagement with one of the rotors, and a second pressureresponsive cheek plate one side of which is in communication with theotherdelivery flow path for maintaining the other rotor in fluid sealingengagement with the first cheek plate.

9. A dual rotary vane pump comprisinga casing provided with a pair ofpumping recesses, a first pumping unit and a second pumping unitseparately mounted in the recesses, each pumping unit including a rotorand a plurality of reciprocating vanes, said vanes being held in bearingcontact with the contour of their respective pumping recesses to formsuction and pressure working chambers, a common drive shaft for therotors, a fluid distributing valve plate floatably mounted in the casingbetween the pumping units, means forming an inlet fluid supply flow pathleading to the suction chamber of the first pumping unit and to thevalve plate, means forming two separate fluid delivery flow paths, oneof which leads from the pressure chamber of the second pumping unit andthe other of which leads from the valve plate, a fluid supply port and afluid delivery port in the valve plate respectively connecting thesuction chamber of the second pumping unit to the inlet supply flow pathand connecting the pressure chamber of the first pumping unit to theother fluid delivery flow path, pressure responsive means including oneside of the valve plate in communication with one of the delivery flowpaths for maintaining the valve plate in fluid sealing engagement withone of the rotors, and a pressure responsive cheek plate having one sidethereof in communication with the other delivery flow path formaintaining the other rotor in fluid sealing engagement with the valveplate.

10. A dual rotary pump. comprising a casing having an inlet section andan outlet section between which is a first pumping unit, means form,-ing a first pressure outlet chamber in the outlet section having anoutlet passage connected thereto, a first pressure responsive cheekplate in the first pressure outlet chamber one side of which ismaintained in fluid sealing engagement against the first pumping unit, asecond pumping unit on the opposite side of the first cheek plate, eachpumping unit including a stator and a rotor iorming suction and pressureworking chambers, a common drive shaft for the rotors, a closure membermounted in the first pressure outlet chamber and forming a secondpressure outlet chamber within the first pressure outlet chamber, asecond cheek plate in the second pressure outlet chamber and pressureloaded against the second pumping unit, means forming an inlet supplyflow path leading from the inlet section to the suction working chambersof the pumping units, means forming two fiuid delivery flow pathsseparately connecting the pressure working chambers of the first andsecond pumping units respectively to the first and second pressureoutlet chambers, a second outlet passage in the outlet section, andmeans hydraulically connecting the second pressure outlet chamber to thesecond outlet passage.

11. A dual rotary pump comprising a casing having an inlet section andan outlet section between which is a first pumping unit, means forming afirst pressure outlet chamber in the outlet section having an outletpassage connected thereto, a first pressure responsive cheek plate inthe first pressure outlet chamber one side of which is 12 maintained influid sealing engagement against the first pumping unit, a secondpumping unit on the opposite side of the first cheek plate, each pumpingunit including a stator and a rotor forming suction and pressure workingchambers, a common drive shaft for the rotors, a closure member mountedin the first pressure outlet chamber and forming asecond pressure outletchamber within the first pressure outlet chamber, a second cheek platein the second pressure outlet chamber and pressure loaded against thesecond pumping unit, means forming an inlet supply flow path leadingfrom the inlet section to the suction working chambers of the pumpingunits, means forming two fluid delivery flow paths separately connectingthe pressure working chambers of the first and second pumping unitsrespectively to the first and second pressure outlet chambers, a secondoutlet passage in the outlet section, and a telescopic connection frominside the second pressure outlet chamber to the second outlet passagehydraulically connecting the second pressure outlet chamber to thesecond outlet passage,

DUNCAN B. GARDINER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,607,383 Aurand Nov. 16, 1926 1,984,664 Teves Dec. 18, 19342,373,457 Chisholm Apr. 10, 1945 2,411,606 Wilson Nov. 26, 1946

